Today's litigious social climate requires an extensive testing regimen of any new product before it is placed on the market. Identifying test compounds that could potentially induce clinical skin irritation is an important step in the product development phase of skin care products. This step is very often performed in animal models such as the rabbit skin irritation test, the maximization test using guinea pigs, the mouse local lymph node assay and the mouse ear swelling test. Because of structural and physiological differences between animal and human skin, the relevance of these methods to the human situation is, however, limited and can lead to misclassification.